Polarized electromagnetic devices



L. S. DISTIN April 10, 1956 POLARIZED ELECTROMAGNETIC DEVICES (POLARIZED RELAY) 2 Sheets-Sheet 1 Filed Aug. 29, 1952 Inventor LIONEL SPARKE- L. S. DlSTlN April 10, 1956 POLARIZED ELECTROMAGNETIC DEVICES (POLARIZED RELAY) Filed Aug. 29, 1952 2 Sheets-Sheet 2 Inventor LmNE SPARKE D/s-rm/ United States Patent POLARIZED ELECTROMAGNETIC DEVICES (POLARIZED RELAY) Lionel Sparke Distin, Chilwell, England, assignor to Eiicsson Telephones Limited, London, England Application August 29, 1952, Serial No. 307,101

9 Claims. (Cl. 317--172) My invention relates to polarized electromagnetic devices, and particularly to contact-operating relays in which an actuating member is adapted to respond in one manner when current flows through a winding in one direction, and in another manner, or not at all, when current flows in the opposite direction.

In some known types of polarized electromagnetic relay one end only of an armature system pivoted at a central point is subjected to the magnetic field produced from the energisation of an actuating electromagnet, whilst in some other known types of such relay both ends of an armature system pivoted at a central point are subjected to the magnetic field or fields of one or more actuating electromagnets. For the purpose of my description I will refer to relays of the former type as half-bridge types, and to relays of the latter type as full-bridge types. One such full-bridge type polarized relay is described in British Patent No. 629,073, and my present invention is in the nature of an improvement on the invention described therein.

In some known forms of half-bridge relay the reluctance of the gap between the pole-piece of the polarizing magnet and the armature is a factor which is used to control the pressure between two adjoining contact faces, and symmetrical pressure between each pair of adjoining contact faces in a change-over contact unit is obtained only when the reluctance between each such pole-piece and the armature is symmetrical or substantially symmetrical. In such relays any unilateral change in the reluctance of the polarizing magnet gap which may occur as a result of physical displacement of the pole-pieces, and/or the permanent magnet, by rough usage or the like will cause a unilateral change in the contact pressures and destroy the symmetry thereof.

The design of some forms of half-bridge type relay is such that the proportion of the actuating magnetic flux which is shunted tends to raise the power required to operate the relay and to reduce its sensitivity, whilst the arrangement of the polarizing magnets in at least one form of such relay tends to make their magnetic characteristics unstable. The mechanical stability of some polarised relays is also impaired by the use of components which are held in position by means of friction, and tend to become'displaced when the relay is subjected to violent movement. In addition the form of the electromagnet coil or coils in some polarized relays is such that the ratio of ampere turns to watts is relativelylow and in consequence the said coils are comparatively inefiicient.

It is one object of my invention to provide a new and improved polarized electromagnetic device wherein the disposition of the component parts and the form of magnetic circuit are such as to provide a polarized relay with one or more change-over contacts in which the symmetry of the contact pressures is substantially unaffected by variations in the polarizing gap reluctance.

It is another object of my invention to provide a polar ized relay having improved sensitivity and increased magnetic and mechanical stability.

It is a further object of my invention to provide a polarized relay of improved electrical efficiency.

According to my invention I provide a polarized electromagnetic device in which an H-shaped armature system comprising two parallel armatures united by a common non-magnetic cross-member and adapted to turn about the centre of the said cross-member embraces the polepieces of an operating electromagnet and is embraced by the pole-pieces of a polarizing permanent magnet.

Again according to my invention I provide a polarized electromagnetic device adapted to respond in one manner when current applied thereto flows in one direction and in a different manner, or not at all, when the current flows in the opposite direction in which the pole-pieces of an electromagnet system lie between two parallel armatures attached to opposite sides of a non-magnetic member adapted to turn about an axis arranged centrally between the pole-pieces of both the electromagnet system and a permanent magnet system.

Other features of my invention will become apparent from the following description of one method of carrying it into effect, and reference should now be made to the accompanying drawings in which:

Fig. 1 shows by means of simple conventions the relation of the basic parts of a polarized device according to my invention.

Fig. 2 shows a perspective view of a complete polarized relay.

Fig. 3 shows a perspective view of a partly disassembled polarized relay.

In Fig. 1 a central non-magnetic member 8 of an armature system pivots about a rod 7 which is arranged to lie parallel with the longitudinal axes of a pair of permanent magnets 1 and their co-axial pole-pieces 2, and parallel with the longitudinal axes of a pair of electromagnet cores 3 and their co-aXial pole-pieces 4. A pair of armature members 6 are arranged parallel to each other on opposite sides of member 8 to which they are attached. Rod 7 on which the armature system formed by members 6 and member 8 turns is held in a position midway between each pair of pole-pieces 2 and 4. The ends of permanent magnets 1 and electromagnet cores 3 remote from polepieces 2 and 4 are connected together magnetically by means of links 9 and 10 respectively which are arranged at right angles to each other. Each electromagnet core 3 is provided with a suitable winding 5, and both such windings are connected in series with each other. Permanent magnets 1, pole-pieces 2 and 4, electromagnet cores 3, and links 9 and 10 are each formed from a magnetic material which is particularly suitable for their part in the magnetic assembly.

The poles of permanent magnets 1 are disposed in such a manner that link 9 connects together an unlike pair of poles, and each pole-piece 2 is of a different polarity. With windings 5 disconnected, and the ends of members 6 located in a midway or so-called centre position equidistant from the most adjacent face of the associated pole-piece 4, the greater part of the permanent magnet flux divides into two substantially equal parts in such a manner that each end of armature member 6 which adjoins the north pole-piece 2 acquires 'a north polarity, and similarly each end of the other member 6 acquires a south polarity, andthe greater part of the said flux passes between the two said members 6 by way of the intervening pole-pieces 4. When both polepieces 4 are located equidistantly from both pole-pieces 2, and each pole-piece 2 is located equidistantly from the point at rod 7 about which body 8 and members 6 turn, a substantially equalpart of the said flux traverses each pole-piece 4. 1 5

When member 8 is turned into a so-called side position where one end of each member 6 adjoins an'associated pole-piece 4, and the other end of each such member 6 is remote from its associated pole-piece 4, the reluctance of both flux paths by way of members 6, the associated air-gaps, and pole-pieces 4 is of the same order, and a substantially equal part of the permanent magnet flux traverses each pole-piece 4. The division of the greater part of the permanent magnet flux into two substantially equal parts each passing by way of one pole-piece 4 of the electromagnet, and both members 6 of the armature system is a characteristic feature of my invention which is retained when either or both of the poles of the permanent magnet system are moved along a path substantially parallel to the longitudinal axis of link 9. With member 8 turned from the centre position towards or into either side position a portion of the permanent magnet flux traverses the main part of the electromagnet system which consists of cores 3 and link 10. The direction and proportion of this flux in the said cores 3 and link 10 is dependent upon the degree to which members 8 are turned from their centre position. Due to the low order of this flux the crosssectional area of core 3 and link 10 may be small in comparison with that of the permanent magnets i, and in a practical embodiment of my invention may be formed of suitable magnetic material of high permeability such as for example a suitable nickel-iron alloy.

Electromagnet cores 3 are polarized when current of suitable value is caused to flow through windings 5, and each pole-piece 4 of the electromagnet system acquires a different polarity. When this occurs with the armature system in the described centre position one end of the member 6 adjacent to pole-piece 2 of north polarity is repelled from electromagnet pole-piece 4 of like polarity, whilst the other end of the same member 6 is attracted towards electromagnet pole-piece 4 of south polarity.

Similarly one end of the member 6 adjacent to polepiece 2 of south polarity is repelled from pole-piece 4 of like polarity, and the other end thereof is attracted towards pole-piece 4 of north polarity. This concurrent attraction and repulsion of opposite ends of each member 6 produces a torque of sufficient moment to rotate the armature system into a side position. When the direction of the current through windings is reversed the polarity of the electromagnet pole-pieces 4 is transposed, the direction of the torque resulting from ,the attraction and repulsion of opposite ends of members 6 is reversed, and the armature system is moved into the other side position.

On the cessation of the current flowing in windings 5 the armature system may be allowed to remain in an actuated position or it may be returned to a previous position by a deflecting spring or other means. An armature system remaining in an actuated position when a How of current ceases is unaffected when current is again caused to flow in the same direction, but is caused to move into another actuated position when current is caused to fiow in the reverse direction. In this manner an armature system may be adapted to respond in one manner when current flows through a winding in one direction, and in another manner when current flows in the opposite direction. In other arrangements the armature system may be caused to move by means of a deflecting spring or other means into one or other of the described actuating positions when the cnergising current ceases, to remain in that position when current flows in one direction, and to respond and move into another position when current flows in the opposite direction.

In the embodiment of my invention in the form of a contact-making relay shown in the accompanying drawings, Fig. 2 shows a relay in which part of a contact carrying post 24 has been removed to clarify the illustration, and Fig. 3 shows a similar relay which has been partly disassembled to illustrate the manner of its construction. The magnet assembly consisting of a pair of electromagnets 15, and a pair of permanent magnets 11, is carried between a non-magnetic base plate 30 and a non-magnetic top-plate 26. The pole-pieces 14 and 12 of the electromagnets 15 and permanent magnets 11 respectively are attached by screws to top plate 26. The core 13 of each electromagnet is attached to a magnetic link 20 and plate 30 by a screw passing through both plate 30 and link 20. The upper end of core 13 passes through plate 26 and is screwed within a pole-piece 14. The pair of permanent magnets 11 are magnetically connected together by means of link 19 which is attached to link 20 and base plate 30. The upper face of each permanent magnet 11 is inclined downwards and outwards and adapted to engage the lower face of polepiece 12 which is inclined in the reverse direction, the lower face of permanent magnet 11 is inclined downwards and inwards and engages with a part of plate 30 which is recessed in the reverse direction, in this manner each permanent magnet 11 is rigidly attached to the magnet structure and cannot easily be displaced therefrom without removing the associated pole-piece 12.

In addition to electromagnet pole-pieces 14 the upper face of plate 26 carries a pivot fixing plate 25, and four posts 24. Each post 24 carries a contact stud in one end of an adjustable threaded shaft 23, the outer end of shaft 23 is provided with a milled cylindrical head 22. The tapped portion of post 24 is slotted, and provided with a screw 31 by means of which shaft 23 may be clamped in any particular position. Each post 24 is insulated from plate 26 by means of suitable insulating washers and screws. Attached to a cylindrical slotted hub in the centre of plate 25 is pivotal member 17 which consists of two U-shaped resilient plates arranged coaxially in reversed positions at right angles to each other. The upper end of pivotal member 17 is fixed in the slotted base of pivotal bracket 32. The forked upper part of pivotal bracket 32 is adapted to engage the central portion of an armature assembly member 18 of non-magnetic insulating material, and is fixed thereto by means of a screw passing horizontally through the centre of the said member 18.

Pivotal member 17 supports a balanced armature system which comprises two armature members 16, four contact springs 21, and four clamping plates 33, each attached to armature assembly member 18 by suitable screws as shown. The contact spring 21 on one face of each arm 34 of member 18 is connected to contact spring 21 on the remote face therefrom to form a single moving contact which, in association with each adjoining contact 23, forms a single change-over contact unit. The relay depicted in Figs. 2 and 3 is provided with two such change-over contacts, alternatively such a relay may be adapted to provide one changeover contact, one make contact and one break contact; or two break contacts and two make contacts. The tapered and rounded end of each contact spring 21 is curved towards the arcuate end of the associated arm 34 and adapted to bear thereon.

Top plate 26 and base plate 30 are maintained in position with respect to each other by four non-magnetic pillars 29. The lower end of each pillar 29 is attached to base plate 30 by means of a screw 35 which passes through base block 27 and base plate 30, and

serves to fix the relay assembly to the said base block 30 of insulating material. The inner face of base block 30 is recessed and furnished with a plurality of connecting pins 28 which pass from the lower and outer face of block .30 to the inner side thereof.

The electrical connections from contact-springs 21 and posts 24 are taken byway of suitable flexible leads, soldered to wiring tags associated with each part, which pass through. channels 37.and holes in top plate 26, and

suitable holes 36 in base plate .30 to connecting pins 28. The connections of the-coils .of electromagnets 15 also pass by way :of holes 36 to connecting pins 28. Connecting pins 28 are adapted to fit within a suitable multipoint socket of known type, and extend the relay connections to external circuiting means.

When the electromagnet 15 of the polarized relay herein described is not energized armature members 16 and the associated armature system may rest in one of three positions namely, with each armature member 16 equidistant from the nearest face of the associated electromagnet polepiece 14, which position I shall term a centre position, or in either of the so-called side positions when one pair or the other of diagonally opposite contact springs 21 are in engagement with their associated fixed contacts 23. The particular polarity which each pole-piece 14 acquires when the associated electromagnet 15 is energised determines the particular side position in which the armature system rests during each such energised period.

The armature system at rest may be made to assume any of the three described positions, or it may be allowed to remain in the side position in which it rested during the preceding energized period of electromagnet 1 In order to set the armature system when at rest into one or the other of the side positions pivotal member 17 is turned about its axis until a contact spring 21 at each end of arm 34 is in close contact with the stud of an associated contact screw 23 at diagonally opposite corners of top plate 26, the hub of pivotal member 17 is then fixed to plate 26. The hub of pivotal mem ber 17 is fixed to plate 26 in such a position that the major axes of arms 34 of member 13 are parallel to the axis of link 20 when the armature system is required to assume a central position during the periods in which electromagnet 15 is not energised. The degree of resiliency of the U-shaped plates forming pivotal member 17 may be considerably greater when a relay is required to operate with side positions only, than when it is required to operate with an armature system having an unoperated central position, as it is found that to maintain an armature system in such a central position the flexibility of the said pivotal member 17 must be re stricted in order to prevent the permanent magnet field alone from actuating the armature system.

The magnetic structure of a relay constructed in the manner described with reference to Figs. 2 and 3 is equivalent to that of the polarized device described with reference to Fig. l and with such a relay the armature system and moving contacts 21 may be caused to assume any one of three positions when the operating electromagnet 15 is not energised, and the greater part of the flux between the permanent magnet pole-pieces 12 passes by way of both armature member 16 and both pole-pieces 14 of the electromagnet 15 without traversing the body of the said electromagnet 15. When a current is caused to flow in the coils of electromagnet 15 in one direction the resultant polarity of pole-pieces 14 is such as to move the armature system from a central position into one side position, and when the said current flows in the reverse direction to move the armature system into the other side position. An armature system at rest in one side position is caused to move into the other side position when a current is caused to flow in the coils of electromagnet 15 in one direction, or to remain at rest in the said position when the current in the electromagnet 15 coils flows in the reverse direction.

The disposition of armature members 16 with regard to permanent magnet pole-pieces 12, and electromagnet pole-pieces 14, in the polarized electromagnet device described previously, is such that the reluctance of the flux path between either or both of pole-pieces 12 and the adjacent armature member 16 may be modified without substantially affecting the symmetrical value of the flux between pole-piece 14 and the adjoining end of an armature member 16. Thus symmetrical pressures between the adjoining faces of each contact unit in such a device may be maintained when the reluctances of the flux paths between the permanent magnet pole-pieces 12 and the armature member 16 are not symmetrical.

In a polarized electromagnetic device embodying my invention the operating electromagnet flux need only be of a low order in comparison with the permanent magnet flux, in consequence the cross-sectional area of the electromagnet core 3 is small in comparison with the cross-sectional area of the permanent magnet, and the efiiciency of the coils wound thereon is high.

The magnetic structure of the polarized electromagnetic device described previously is such that the ratio of the active pole-face area to the total pole-face area is high, whilst the magnetic leakage, particularly of the actuating electromagnet system, is of a very low order. Also the magnets in the permanent magnet system are attached in a manner which enables them to be removed for the purpose of clearing magnetic particles without disturbing the adjustment of the device, and their polarity is arranged in an order which tends to preserve their magnetic stability.

The magnetic and mechanical stability of the polarized device embodying my invention is of a high order in consequence of the location of all pole-pieces of the electromagnetic and polarizing magnet system by means of one plate which determines their position with regard to each other, and whichthey are fixed in such a manner that the value of each magnetic gap does not depend on clamped frictionally held members for its constancy.

It is a feature of the polarized electromagnetic contact operating device described with reference to Figs. 2 and 3 that the contact and magnetic gaps are readily accessible for gauging, whilst the contact springs may be removed Without disturbing the adjustment of the magnetic circuit.

I do not confine my invention to contact-operating devices as herein described, and in other applications of my invention the oscillatory movement of the armature system may be employed to actuate a pawl and ratchet mechanism and to rotate, for example, the shaft and Wipers of a selector switch. Other applications of the movement of the armature system will become apparent to those skilled in the art after the basic principles dc scribed previously are understood.

What I claim is:

1. In a polarized electromagnetic device, the combination of a double armed permanent polarizing magnet system, a double armed electromagnet system having its arms symmetrically arranged equidistantly from the arms of the permanent magnet system each such magnet system including a magnetic bridge piece connecting its arms together at one end, a magnetic connection between the bridge pieces of said system positioned midway between the arms of each system, an H shaped armature, means pivotally mounting said armature between the arms of the permanent magnet system in such position as to embrace at its ends the arms of the electromagnet system and means for energising the electromagnet system to set up a magnetic flux tending to deflect said armature in a direction determined by the direction of said flux.

2. In a polarized electromagnetic device, the combination of a double armed permanent polarizing magnet system having parallel arms and pole pieces at cor responding ends of its arms, a double armed electromagnet system having its arms parallel and arranged equidistantly from the arms of the permanent magnet system and pole pieces at corresponding ends of its arms, each said magnet system including a magnetic bridge piece connecting its arms together at their ends remote from the pole pieces, a magnetic connection between the bridge pieces of said systems positioned centrally between the arms of each system, an H shaped armature system, means pivotally mounting said armature system with its central portion embraced between the pole pieces of the permanent magnet system and in such a position as to embrace at its ends the pole pieces of the electromagnet system, and means for energising the electromagnet system to set up a magnetic flux therein whereby to deflect said armature system in a direction determined by the direction of said flux.

3. In a polarized electromagnetic device, the combination of a double armed permanent polarising magnet system. having parallel arms, a double armed electromagnetic system whereof the arms are parallel and symmetrically arranged equidistantly from the arms of the permanent magnet system, each said magnet system including at least one magnetic link connecting its arms at one end said links being connected magnetically midway between the arms of each magnet system, an H shaped armature system including two parallel magnetic armatures and a nonmagnetic cross-member supporting them centrally, means pivotally mounting said armature system. with its central portion between the arms of the permanent magnet system and in such a position as to embrace between the ends of said armaturcs the arms of said electromagnet system, and means for energising the electromagnet system to set up therein a magnetic flux whereby to deflect said armature system in a direction determined by the direction of said flux.

4. In a polarized electromagnetic device, the combination as claimed in claim 3 wherein the means for pivotally mounting said armature system comprises two slotted plates interengaged at right angles to one another, means connecting said plates at one end to said nonmagnetic cross-member and a bearing in which said plates are pivotally mounted.

5. In a polarized electromagnetic device, the combination of a permanent polarizing magnet system comprising two parallel pole arms connected magnetically at one end, an electromagnet systenrcomprising two pole arms parallel to and equidistant from the pole arms of the permanent magnet system and connected magnetically at the same end, means uniting said magnet systems to one another midway between said arms, an H shaped armature system comprising parallel armatures and a non-magnetic bridge piece supporting them centrally, a pivotal mounting carrying said bridge piece so as to mount the armatures with their central portions between the pole arms of the permanent magnet system and with their ends respectively embracing the pole arms of the electromagnet system, and means whereby said electromagnet system may be energized to deflect said armature system in a direction determined by that or the energising flux.

6. In a polarized electromagnetic device, the combination of a permanent polarizing magnet system comprising two parallel pole arms connected magnetically at one end, an electromagnet system comprising two pole arms parallel to and equidistant from the pole arms of the permanent magnet system and connected magnetically at the same end, means uniting said magnet systems to one another midway between their arms, pole pieces on the ends of all of said pole arms remote from their magnetically connected ends, a non-magnetic plate through apertures in which said pole pieces extend to locate them, an H-shaped armature system comprising a non-magnetic bridge piece and armatures mounted in parallel arrangement on opposite sides of said bridge piece, a pivotal mounting carrying said bridge piece so as to support said armatures pivetally with their central portions between the pole pieces of the permanent magnet system and with their ends respectively embracing the pole pieces of the electromagnet system, and means whereby said eleetromagnet system may be energised to deflect said armature system in a direction determined by that of the energising flux.

7. The combination according to claim 6 comprising fixed electrical contacts associated with the ends of said armature system and movable flexible electrical contact springs positioned on the bridge piece of said armature system to co-operate respectively with said fixed electrical contacts.

8. The combination according to claim 7 comprising a further plate between which and said non-magnetic plate the said magnet systems are mounted and means coupling said plates to maintain the said magnet systems in constant relationship with respect to each other' 9. The combination according to claim 5 comprising fixed electrical contacts, means supporting said fixed contacts adjacent the ends of said armature system, endwise proiections on the said bridge piece of the armature system, and flexible electric contact springs carried on said projections to cooperate respectively with said fixed contacts, said contact springs being so arranged that the free end of each of them will engage frictionally with a portion of the appropriate projection to damp vibratory movement of the spring on engagement and disengagement with the appropriate fixed contact.

References Qited in the file of this patent UNITED STATES PATENTS 838,192 Kitsee Dec. 11, 1906 920,036 Dodgson Apr. 27, 1909 1,562,646 Kaisling Nov. 24, 1925 1,743,478 Pratt Ian. 14, 1930 1,795,439 Pratt Mar. 10, 1931 1,795,499 Miller et al Mar. 10, 1931 2,458,939 Hall Jan. 11, 1949 FOREIGN PATENTS 517,001 Great Britain Jan. 17, 1940 629,073 Great Britain Sept. 9, 1949 

